There is a film forming apparatus having two processing regions provided inside one vacuum container and being incompletely partitioned by a separation region to which a separation gas is supplied. In this film forming apparatus, different reaction gases are supplied to the two processing regions, respectively.
Incidentally, in the case where the two processing regions are incompletely partitioned, when the pressure in the vacuum container or the flow rate of the reaction gases are suddenly changed, the reaction gases may flow out from one processing region to the other and may be mixed in some cases.
Thus, in the related art, exhaust paths are provided individually in respective processing regions, and a separation region is provided between the processing regions. The ratio of flow rates of gases to be exhausted from the exhaust paths and the pressure inside a vacuum container are adjusted so that the gas flow toward a substrate becomes constant.
However, in the above technique, the adjustment of the gas flow rate ratio and the adjustment of the pressure inside the vacuum container are alternately repeated when changing conditions including a pressure. Therefore, the adjustment is time-consuming, and there is room for improvement from the viewpoint of productivity.